Toshiba RAS-10UKV-E Service Manual page 24

(3) Contents of operation command signal (Serial
signal) from indoor unit controller to outdoor unit
controller
The following three types of signals are sent from
the indoor unit controller.
• Operation mode set on the remote control
• Compressor revolution command signal defined
by indoor temperature and set temperature
(Correction along with variation of room
temperature and correction of indoor heat
exchanger temperature are added.)
• For these two types of signals ([Operation mode]
and [Compressor revolution]), the outdoor unit
controller monitors the input current to the
inverter, and performs the followed operation
within the range that current does not exceed
the allowable value.
• Temperature of indoor heat exchanger by indoor
heat exchanger sensor
(Minimum revolution control)
(4) Contents of operation command signal (Serial
signal) from outdoor unit controller to indoor unit
controller
The following signals are sent from the outdoor
unit controller.
• The current operation mode
• The current compressor revolution
• Outdoor temperature
• Existence of protective circuit operation
For transferring of these signals, the indoor unit
controller monitors the contents of signals, and
judges existence of trouble occurrence.
Contents of judgement are described below.
• Whether distinction of the current operation
status meets to the operation command signal
• Whether protective circuit operates
When no signal is received from the outdoor unit
controller, it is assumed as a trouble.
8-1-1. Capacity control
The cooling and heating capacity is varied by changing
compressor motor speed. The inverter changes
compressor motor speed by changing AC 220-240V
power to DC once, and controls capacity by changing
supply power status to the compressor with transistor
module (includes 6 transistors). The outline of the
control is as follows:
The revolution position and revolution speed of the
motor are detected by detecting winding electromotive
force of the compressor motor under operation, and
the revolution speed is changed so that the motor
drives based upon revolution speed of the operation
command by changing timing (current transfer timing)
to exchange inverter output voltage and supply power
winding.
Detection of the revolution position for controlling is
performed 12 times per 1 revolution of compressor.
The range of supply power frequency to the compressor
differs according to the operation status (COOL, HEAT,
DRY).
Table 8-1-1 Compressor revolution range
Operation mode
COOL
HEAT
8-1-2. Current release control
The outdoor main circuit control section (Inverter
assembly) detects the input current to the outdoor unit.
If the current value with compressor motor speed
instructed from indoor side exceeds the specified
value, the outdoor main circuit control section controls
compressor motor speed by reducing motor speed so
that value becomes closest to the command within the
limited value.
8-1-3. Power factor improvement control
Power factor improvement control is performed mainly
aiming to reduce the current on much power consump-
tion of cooling/heating operation. Controlling starts
from the time when input power has reached at a
certain point. To be concrete, IGBT of the power factor
improvement circuit is used, and the power factor is
improved by keeping IGBT on for an arbitrary period to
widen electro-angle of the input current.
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FILE NO. SVM-02007
Compressor revolution (rps)
21 to 66
21 to 83